Expose IntraLineDiffKey components with public getters

Grabbing these might be handy in a custom cache implementation
that needs to serialize the IntraLineDiffKey.

Change-Id: I51aec72f2c5409479116696b3b345dd4b8846c6c

gerrit-server/src/main/java/com/google/gerrit/server/patch/IntraLineDiffKey.java

@@ -70,11 +70,11 @@ public class IntraLineDiffKey implements Serializable {
     return edits;
   }
 
-  ObjectId getBlobA() {
+  public ObjectId getBlobA() {
     return aId;
   }
 
-  ObjectId getBlobB() {
+  public ObjectId getBlobB() {
     return bId;
   }